Project description:The advent of human induced pluripotent stem (iPS) cells enables for the first time the derivation of unlimited numbers of patient-specific stem cells and holds great promise for regenerative medicine. However, realizing the full potential of iPS cells requires robust, precise and safe strategies for their genetic modification. Safe human iPS cell engineering is especially needed for therapeutic applications, as stem cell-based therapies that rely on randomly integrated transgenes pose oncogenic risks. Here we describe a strategy to genetically modify iPS cells from patients with beta-thalassemia in a potentially clinically relevant manner. Our approach is based on the identification and selection of âsafe harborâ sites for transgene expression in the human genome. We show that thalassemia patient iPS cell clones harboring a transgene can be isolated and screened according to chromosomal position. We next demonstrate that iPS cell clones that meet our âsafe harborâ criteria resist silencing and allow for therapeutic levels of beta-globin expression upon erythroid differentiation without perturbation of neighboring gene expression. Combined bioinformatics and functional analyses thus provide a robust and dependable approach for achieving desirable levels of transgene expression from selected chromosomal loci. This approach may be broadly applicable to introducing therapeutic or suicide genes into patient specific iPS cells for use in cell therapy. iPS cell clones were derived from beta-thalassemia patients. A single copy of beta-globin transgene cis-linked to locus control region (LCR) elements and an excisable Neo-eGFP transcription unit were inserted into these cell clones. beta-globin expression was induced by erythroid differentiation.
Project description:The advent of human induced pluripotent stem (iPS) cells enables for the first time the derivation of unlimited numbers of patient-specific stem cells and holds great promise for regenerative medicine. However, realizing the full potential of iPS cells requires robust, precise and safe strategies for their genetic modification. Safe human iPS cell engineering is especially needed for therapeutic applications, as stem cell-based therapies that rely on randomly integrated transgenes pose oncogenic risks. Here we describe a strategy to genetically modify iPS cells from patients with beta-thalassemia in a potentially clinically relevant manner. Our approach is based on the identification and selection of “safe harbor” sites for transgene expression in the human genome. We show that thalassemia patient iPS cell clones harboring a transgene can be isolated and screened according to chromosomal position. We next demonstrate that iPS cell clones that meet our “safe harbor” criteria resist silencing and allow for therapeutic levels of beta-globin expression upon erythroid differentiation without perturbation of neighboring gene expression. Combined bioinformatics and functional analyses thus provide a robust and dependable approach for achieving desirable levels of transgene expression from selected chromosomal loci. This approach may be broadly applicable to introducing therapeutic or suicide genes into patient specific iPS cells for use in cell therapy.
Project description:Delta-Beta thalassemia is an unusual variant of thalassemia caused by large deletions in the β globin gene cluster involving δ- and β-globin genes. The mutations are characterized by high fetal hemoglobin with significant phenotypic diversity. Routinely used diagnostic tests targeting point mutations and small insertions, deletions of the β-globin gene are not suitable for detection of large deletion mutations. This is overcome by either direct globin chain synthesis analysis or beta-cluster gene analysis using different methods. In the current study, we use direct globin chain analysis to diagnose a family with δβ-thalassemia using high resolution mass spectrometry.
Project description:Reactivation of gamma-globin is considered a promising approach for the treatment of beta-thalassaemia and sickle cell disease. Therapeutic induction of gamma-globin expression is fraught with lack of suitable therapeutic targets. In order to identify new potential targets we analysed the changes in the proteome of human primary erythroid progenitor cells by treatment with decitabine, a known, yet not clinically safe, gamma-globin inducer. Significant differentially expressed proteins were identified which were involved in various biological pathways and functional categories.
2020-01-23 | PXD006889 | Pride
Project description:Genomic safe harbors from endogenized parvovirus loci
Project description:Clinical application of induced pluripotent stem (iPS) cells is limited by low efficiency of iPS derivation, and protocols that permanently modify the genome to effect cellular reprogramming. Moreover, safe and effective means of directing the fate of patient-specific iPS cells towards clinically useful cell types are lacking. Here we describe a simple, non-mutagenic strategy for reprogramming cell fate based on administration of synthetic mRNA modified to overcome innate anti-viral responses. We show that this approach can reprogram multiple human cell types to pluripotency with efficiencies that greatly surpass established protocols. We further show that the same technology can be used to efficiently direct the differentiation of RNA-induced pluripotent stem (RiPS) cells into terminally differentiated myogenic cells. Our method represents a safe, efficient strategy for somatic cell reprogramming and directing cell fates that has broad applicability for basic research, disease modeling and regenerative medicine. We isolated RNA from human RNA derived iPS cells, viral derived iPS cells, different human fibroblasts and human embryonic stem cells for hybridization to the Affymetrix gene expression microarrays.
Project description:β-Thalassemia is a prevalent anemia caused by mutations in the HBB (β-globin) gene. We show that the severity of β-thalassemia in the frequently studied Hbbth3/+ mouse model is influenced by ancestral β-globin gene (Hbb) haplotypes that differ in common strains.
Project description:beta-Thalassemia is a prevalent anemia caused by mutations in the HBB (beta-globin) gene. We show that the severity of beta-thalassemia in the frequently studied Hbb(th3/+) mouse model is influenced by ancestral beta-globin gene (Hbb) haplotypes that differ in common strains.
Project description:The reactivation of developmental silenced g-globin genes (HBG1/2) has shown promise as a therapeutic strategy for improving symptoms of b-hemoglobinopathies. Currently, the focus of therapeutic targets is primarily on the major fetal hemoglobin suppressors, such as BCL11A and ZBTB7A and of their binding sites on the proximal HBG promoter. However, the role of the distal HBG promoter in regulating gene expression remains to be explored. Here, we discovered an insertion of nucleotide A (insA) between -1368 and -1369 bp upstream of the TSS in HBG2 resulting in remarkable increase in γ-globin expression in HUDEP-2 cells. We also observed elevated γ-globin expression in human CD34+ erythroid progenitor cells from healthy individuals and those with b-thalassemia when introducing insA mutation. Similarly, engrafted NCG-Kit-V831M mice showed increased γ-globin expression. Importantly, neither did insA have any off-target effects nor did it affect the maturation of erythroid cells. Furthermore, we found that the insA mutation created a binding site for the transcription activator FOXO3, which can reactivate g-globin. Additionally, introducing insA specifically and significantly demethylated the -162 CpG site on HBG promoter by reducing the enrichment of DNA methyltransferase 3A (DNMT3A). At the same time, it activated histone modifications and RNA polymerase II (Pol II) in both distal and proximal HBG promoter and inhibited the binding of BCL11A and ZBTB7A on -115 and -200 sites on the HBG promoter respectively. Overall, our study suggests that introducing insA mutation leads to significantly boosted fetal globin levels and uncovers new safe therapeutic target or strategy for β-hemoglobinopathies.